class Bill(db.Model):
    __tablename__ = "bill"

    bill_id = db.Column(db.Integer, primary_key=True, unique=True)
    student_id = db.Column(db.Integer, db.ForeignKey('student.student_id'))
    course_id = db.Column(db.Integer, db.ForeignKey('course.course_id'))
    course_price = db.Column(db.Float)
    hasBeenPaid = db.Column(db.Boolean, default=False)